This invention relates to gas turbine engine seals, and in particular gas turbine engine stator well seals.
Axial flow turbomachines such as gas turbine engines are often constructed in such a way that the platform sections of adjacent blades combine to form the inner flow boundary of the machine's annular gas flow path. Since the gas path usually extends over a plurality of adjacent stages the flow boundary often comprises both stator and rotor blade platforms. Seals are provided between the adjacent rotatable and non-rotatable platform sections to prevent working fluid leakage from the gas flow path during engine operation.
In a known arrangement the rotor blades locate in axial root slots formed in the circumferential periphery of a rotor disc, and the stator vanes in adjacent stator vane support structure which may also define the stator vane platform flow boundary. An annular seal member is provided which extends from the periphery of the rotor disc towards the adjacent stator vane support structure to seal the gap therebetween. The seal member is attached to the disc by bolts or the like, and forms a labyrinth type seal with the underside of the stator vane platform or vane support structure at it's distal end.
A problem with this approach is that disc/seal member assembly considerations tend to compromise the seal design. Large stator well volumes often result in the region between the disc periphery and the stator vane support structure. These voids are undesirable since they tend to upset the aerodynamic stability of the gas flow through the annular flow path during engine operation. In axial flow compression systems this can have a severe impact on the stability characteristics of the compressor.